The present invention relates to packaging machines, and more particularly to a packaging machine adapted to form a tube from a web serving as a packaging material, fill contents into the tube, cut the content-filled tube into lengths each corresponding to one container and finally make the lengths of tube into rectangular parallelepipedal containers.
The web for use with machines for preparing aseptic packages is a paper-base laminate including aluminum foil, but since this type of laminate is expensive, paper-base laminates having no aluminum foil are used for machines not adapted for asceptic packaging.
Packaging machines heretofore known for use with a web of paper-base laminate having no aluminum foil comprise a transport device for transporting the web along a specified path, a tube forming unit for forming the web into a vertical tube, a filling unit for filling contents into the tube, and a container forming unit for forming the content-filled tube into baglike containers. The container forming unit has jaws for clamping the content-filled tube at regular lengthwise intervals each corresponding to one container to heat-seal the tube over a required width and cut the tube at the midportion of the seal width. The jaws are provided with a heating plate for heat sealing.
With the conventional packaging machine, the heating plate is used as a heater, so that unless the temperature of the heating plate is fully controlled, the portion to be sealed will be melted insufficiently or excessively and will not always be sealed off properly. Further because the portion to be sealed off is heated from outside the laminate, the machine has the problem of necessitating a considerable period of heating time.